US7344943B2

Method for forming a trench MOSFET having self-aligned features

Summary by NHIP

Trench MOSFET Formation

The method forms trenches in silicon and creates self-aligned source regions by removing exposed silicon adjacent to trench sidewalls. This process generates contact openings between every two adjacent trenches while leaving only the doped portions next to the sidewalls intact.

Claim Score by NHIP

Read claim 1, the broadest

Abstract

A semiconductor device is formed as follows. A plurality of trenches is formed in a silicon layer. An insulating layer filling an upper portion of each trench is formed. Exposed silicon is removed from adjacent the trenches to expose an edge of the insulating layer in each trench, such that the exposed edge of the insulating layer in each trench defines a portion of each contact opening formed between every two adjacent trenches.

US7344943B2, drawing sheet 1 — Sheet 1 of 10

Term

Term ended

Expired 25 April 2024, 2.4 years ago.

11 claims: 2 independent, 9 dependent

1
Broadest claimClaim Score 59, broad(NHIP)A method of forming a semiconductor device, comprising:forming a plurality of trenches in a silicon layer;forming a first doped region of a first conductivity type in an upper portion of the silicon layer;forming an insulating layer within each trench such that a top surface of the insulating layer is substantially coplanar with a top surface of the first doped region, the insulating layer in each trench extending directly over a portion of the first doped region adjacent each trench sidewall;and removing exposed silicon from adjacent each trench until, of the first doped region, only the portions adjacent the trench sidewalls remain, the remaining portions of the first doped region adjacent the trench sidewalls forming source regions which are self-aligned to the trenches.
7
A method of fabricating a semiconductor device, comprising:forming a plurality of trenches in a silicon layer;forming a gate electrode partially filling each trench;forming a first doped region of a first conductivity type in an upper portion of the silicon layer;forming an insulating layer within each trench such that a top surface of the insulating layer is substantially coplanar with a top surface of the first doped region, each trench having a contour such that the insulating layer in each trench extends directly over a portion of the first doped region adjacent each trench sidewall;and removing exposed silicon from between adjacent trenches such that: 1) a contact opening is formed between every two adjacent trenches, and 2) of the first doped region, only the portion adjacent each trench sidewall remains, the portion of the first doped region remaining adjacent each trench sidewall forming a source region.

Independent claims2

35 paragraphs in 5 sections, as filed

This application is a division of and claims priority to U.S. application Ser. No. 10/442,670, filed May 20, 2003, U.S. Pat. No. 6,916,745, which disclosure is incorporated herein by reference for all purposes.

BACKGROUND OF THE INVENTION

The present invention relates to semiconductor MOSFET technology and more particularly to a trench MOSFET having self-aligned features.

Power MOSFETs (metal oxide semiconductor field effect transistors) are well known in the semiconductor industry. One variety of power MOSFETs is the vertically-conducting trench MOSFET. A cross-section view of such a MOSFET is shown in <figref idref="DRAWINGS">FIG. 1</figref>. MOSFET 100 has trenches 111 each including a polysilicon gate 112 insulated from body regions 114 by a gate dielectric 110. Source regions 116 flank each side of trenches 111. Dielectric layer 120 insulates gates 112 from overlying metal layer 126. Substrate region 102 forms the drain of MOSFET 100.

When MOSFET 100 is biased in the on state, current flows vertically between source regions 116 and substrate 102. The current capability of MOSFET 100 in the on state is a function of the drain to source resistance (Rdson). To improve the current capability of the MOSFET, it is necessary to reduce the Rdson. One way to reduce the Rdson of the trench MOSFET is to increase the trench density (i.e., to increase the number of trenches per unit area). This may be achieved by reducing the cell pitch. However, reducing the cell pitch of MOSFETs is limited by the particulars of the MOSFET cell structure and the specific process recipe used to manufacture the MOSFET. Reducing the cell pitch is made further difficult by such limitations of the manufacturing process technology as the minimum critical dimensions the photolithography tools are configured to resolve, the minimum required spacing between different cell regions as dictated by the design rules, and the misalignment tolerances.

The different dimensions that determine the minimum cell pitch for trench MOSFET 100 are shown in <figref idref="DRAWINGS">FIG. 1</figref>. Dimension A is the minimum trench width the photolithography tools are configured to resolve, dimension B is the minimum contact opening the photolithography tools are configured to resolve, dimension C is the minimum trench-to-contact spacing dictated by the design rules, and dimension D is the contact registration error tolerance or contact misalignment tolerance. The minimum cell pitch for MOSFET 100 thus equals A+B+2C+2D. Reduction of any of these dimensions without complicating the process technology is difficult to achieve.

Thus, a new approach wherein the cell pitch of the trench MOSFET can be reduced without increasing the process complexity is desirable.

BRIEF SUMMARY OF THE INVENTION

In accordance with an embodiment of the present invention, a semiconductor device is formed as follows. A plurality of trenches is formed in a silicon layer. An insulating layer filling an upper portion of each trench is formed. Exposed silicon is removed from adjacent the trenches to expose an edge of the insulating layer in each trench such that the exposed edge of the insulating layer in each trench defines a portion of each contact opening formed between every two adjacent trenches.

In one embodiment, prior to removing exposed silicon, a first region of a first conductivity type is formed in the silicon layer such that after the step of removing the exposed silicon, only a portion of the first region adjacent each trench sidewall remains. The remaining portion of the first region adjacent each trench sidewall forms a source region of the semiconductor device. The step of removing the exposed silicon further exposes a sidewall of each source region such that the exposed edge of the insulating layer in each trench together with the exposed sidewall of a corresponding source region form one sidewall of a contact opening between every two adjacent trenches.

In another embodiment, a gate electrode filling a lower portion of each trench is formed, such that the insulating layer substantially fills a remaining portion of each trench.

The following detailed description and the accompanying drawings provide a better understanding of the nature and advantages of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

<figref idref="DRAWINGS">FIG. 1</figref> shows a cross-section view of a conventional trench MOSFET;

<figref idref="DRAWINGS">FIGS. 2A-2K</figref> show cross-section views at different stages of manufacturing a trench MOSFET in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 3</figref> is a graph showing the effect of cell pitch reduction on Rdson;

<figref idref="DRAWINGS">FIGS. 4A and 4B</figref> show an alternate method for forming trenches in accordance with another embodiment of the invention; and

<figref idref="DRAWINGS">FIG. 5</figref> is an exemplary cross-section view corresponding to that in <figref idref="DRAWINGS">FIG. 2K</figref>, and is provided to show a more accurate representation of the contours of the trenches in accordance with one embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, a structure and method for forming a trench MOSFET having self-aligned features which result in cell pitch reduction without increasing the process complexity are disclosed. In one embodiment, trenches are formed in an epitaxial layer in such manner that the trench sidewalls fan out near the top of the trench over source regions. An insulating layer formed along a top portion of each trench together with the source regions defines the contact openings between adjacent trenches for contacting the source and body regions. This structure and method of forming the trenches leads to a MOSFET which has source regions and contact openings self-aligned to the trenches. This in turn enables the 2D portion of the cell pitch of prior art MOSFET 100 (<figref idref="DRAWINGS">FIG. 1</figref>) to be eliminated and the dimension B to be reduced to thus obtain a reduced cell pitch without introducing any process complexities

<figref idref="DRAWINGS">FIGS. 2A-2K</figref> are cross-section views at different stages of manufacturing a trench MOSFET in accordance with an embodiment of the present invention. In <figref idref="DRAWINGS">FIG. 2A</figref>, a lightly doped N-type epitaxial layer 204 extends over a highly-doped N-type substrate 202. A layer of a material which is resistant to silicon etch having a thickness in the range of 2,000-10,000 Å is formed over epitaxial layer 204. In one embodiment, an oxide layer having a thickness of about 5,000 Å is used. Using a masking step, predefined portions of the layer of material resistant to silicon etch are removed so that only regions 206 remain. In the embodiment wherein an oxide layer is used, conventional dry or wet etch may be used to remove the predefined portions of the oxide layer.

In <figref idref="DRAWINGS">FIG. 2B</figref>, a first silicon etch is carried out to form a mid-section 208 of a plurality of trenches. The spacing between regions 206 defines the width of mid-section 208 which is in the range of 0.2-2.0 μm. Mid-section 208 extends from the exposed surface areas of epitaxial layer 204 to a depth in the range of 0.5-3.0 μm. In one embodiment, the width and depth of mid-section 208 are about 0.35 μm and 1.0 μm, respectively. Conventional methods for etching silicon, for example, reactive ion etching (REI), may be used to form mid-section 208 of the trenches.

In <figref idref="DRAWINGS">FIG. 2C</figref>, portions of regions 206 are removed to expose additional surface areas 207 of epitaxial layer 204. Smaller regions 206a having a thickness in the range of 1,000-9,000 Å thus remain. In the embodiment where regions 206 are from oxide, regions 206 are isotropically etched so that smaller oxide regions 206a having a thickness of about 2,500 Å remain.

In <figref idref="DRAWINGS">FIG. 2D</figref>, a second silicon etch is carried out to remove portions of epitaxial layer 204 along its exposed surfaces to thereby form outer sections 208b of the trenches. As shown, mid-section 208a extends deeper than outer sections 208b. Outer sections 208b extend from surface areas 208b of epitaxial layer 204 to a depth in the range of 0.1-1.0 μm. In one embodiment, the depth of outer sections 208b is about 0.4 μm. Note that the second silicon etch also removes silicon from along the bottom of the mid-section 208 though it is not necessary to do so. As with the first silicon etch, conventional methods for etching silicon, for example, reactive ion etching (REI), may be used for the second silicon etch.

While <figref idref="DRAWINGS">FIGS. 2A-2D</figref> show one method for forming trenches having a deep mid-section and shallow outer sections, the invention is not limited to this particular method. For example, an alternate method for forming trenches having similar physical characteristics is shown in <figref idref="DRAWINGS">FIGS. 4A and 4B</figref>. After forming isolated regions 206 of for example oxide or photoresist, as in <figref idref="DRAWINGS">FIG. 2A</figref>, an isotropic silicon etch is carried out so that openings 203 are created in epitaxial layer 204 between adjacent regions 206 as shown in <figref idref="DRAWINGS">FIG. 4A</figref>. The isotropic etch removes silicon from under regions 206 as shown. Next, keeping regions 206 intact, a conventional silicon etch is carried out to form deeper mid-sections 203a of the trenches as shown in <figref idref="DRAWINGS">FIG. 4B</figref>. As can be seen, each trench has a deep mid-section 203a and shallow outer sections 203b extending under regions 206.

Referring back to <figref idref="DRAWINGS">FIGS. 2A-2K</figref>, in <figref idref="DRAWINGS">FIG. 2E</figref>, remaining regions 206a may optionally be removed at this stage of the process. An insulating layer 210 is then formed along the surface of epitaxial layer 204 using conventional methods. Sidewalls of the trenches are thus coated with insulating layer 210. Insulating layer 210 has a thickness in the range of 50-1,000 Å. In one embodiment, insulating layer 210 is a gate oxide having a thickness of about 400 Å.

Next, using conventional polysilicon deposition techniques, a polysilicon layer 212 having a thickness in the range of 1,000-15,000 Å is deposited over insulating layer 210 to fill the trenches. In one embodiment, polysilicon layer 212 has a thickness of about 5,500 Å and is doped with impurities. In yet another embodiment, prior to forming polysilicon layer 212, a thick insulating layer is formed along the bottom of the mid-section 208a of the trenches. This advantageously reduces the gate capacitance of the MOSFET.

In <figref idref="DRAWINGS">FIG. 2F</figref>, polysilicon layer 212 is etched back to form gates 212a in mid-section 208a of the trenches. Polysilicon layer 212 is etched back such that its upper surface is recessed below the outer sections 208b of the trenches. This insures that no polysilicon is left in the outer sections 208b of the trenches which may otherwise short the gate to the source and also block the source and body implants carried out later in the process. However, the extent to which the polysilicon layer 212 is etched back must be carefully controlled to insure that at least a portion of the gate overlaps with the source regions formed in later steps. Conventional polysilicon etching techniques may be used to etch back polysilicon layer 212.

P-type body regions 214 are then formed in epitaxial layer 204 between adjacent trenches by implanting P-type impurities such as boron. The P-type implant is symbolically shown by arrows 218 which indicate that no mask is needed. Body regions 214 extend into epitaxial layer 204 to a depth primarily dictated by the target channel length. Next, highly-doped N-type regions 216 are formed in body regions 214 by implanting N-type impurities such as arsenic or phosphorous. N-type regions 216 extend along the top surface of body regions 214 and directly below outer sections 208b of the trenches. The N-type implant is symbolically shown by arrows 219 which indicate that no masking is needed for this implant either. Conventional ion implantation techniques may be used for both implant steps.

In <figref idref="DRAWINGS">FIG. 2G</figref>, a dielectric layer 220, such as BPSG, is formed over the entire structure using conventional techniques. Dielectric layer 220 has a thickness in the range of 2,000-15,000 Å. In one embodiment, the thickness of dielectric layer 220 is about 8,000 Å. Next, a conventional dielectric flow step is carried out to obtain a planar surface as shown in <figref idref="DRAWINGS">FIG. 2H</figref>. Dielectric layer 220a is then etched until silicon is reached as shown in <figref idref="DRAWINGS">FIG. 2I</figref>. After the dielectric etch, dielectric regions 220b which are fully contained in the trenches remain while surface areas of N-type regions 216 are exposed.

In <figref idref="DRAWINGS">FIG. 2J</figref>, a conventional silicon etch is carried out to form contact openings 222. Sufficient amount of silicon is removed so that along with the upper portion of N-type regions 216 a top layer of body regions 214 is also removed. This insures that: (i) a top surface of body regions 214a becomes exposed so that contact can be made to body regions 214a, (ii) of N-type region 216, source regions 216a separated by body regions 214a remain, and (iii) sidewall areas of source regions 216a become exposed so that contact can be made to source regions 216a. In <figref idref="DRAWINGS">FIG. 2K</figref>, metal layer 226 is deposited to contact body regions 214a and source regions 216a. Before metal 226 is deposited, a layer of heavily doped P-type region 224 may optionally be formed along the top surface of body regions 214a using conventional ion implantation techniques. The heavily doped region 224 helps achieve an ohmic contact between metal 226 and body region 214a. As shown, metal layer 224 is insulated from gates 212a by the dielectric layer 220b extending along the top surface of each trench.

Referring back to <figref idref="DRAWINGS">FIG. 2J</figref>, the silicon etch carried out to form contact openings 222 exposes portions of insulating layer 210 extending along the sidewalls of outer sections 208b of the trenches. As can be seen, the exposed portions of insulating layer 210 together with the exposed sidewall area of source regions 216a advantageously define contact openings 222 between adjacent trenches. Thus, with no masking steps used in forming either source regions 216a or contact openings 222, source regions 216a and contact openings 222 which are self-aligned to the trenches are formed.

Because source regions 216a and contact openings 222 are self-aligned to the trenches, the need to account for contact misalignment as in conventional techniques (dimension D in <figref idref="DRAWINGS">FIG. 1</figref>) is eliminated. Furthermore, the contact openings (dimension B in <figref idref="DRAWINGS">FIG. 1</figref>) can be made smaller than the photolithography tools are typically configured to resolve. Thus, not only the 2D term is eliminated from the minimum cell pitch A+B+2C+2D of the conventional trench MOSFET in <figref idref="DRAWINGS">FIG. 1</figref>, but the term B can be made much smaller. For the same process technology, a much smaller cell pitch is therefore obtained without increasing the process complexity.

The small cell pitch results in an increase in the number of trenches per unit area which in turn has the desirable effect of lowering the Rdson. This is more clearly shown in <figref idref="DRAWINGS">FIG. 3</figref>. <figref idref="DRAWINGS">FIG. 3</figref> is a graph showing the effect of cell pitch reduction on Rdson. The vertical axis represents Rdson and the horizontal axis represents the cell pitch. The numbers along the vertical axis are merely illustrative and do not reflect actual values of Rdson. Two curves are shown with the upper curve corresponding to a gate-source bias of 4.5V and the lower curve corresponding to a gate-source bias of 10V. For the same process technology, the self-aligned features of the present invention result in a reduction of the cell pitch from 1.8 μm to 1.0 μm. This cell pitch reduction results in about a 30% reduction in Rdson in the case of 10V biasing and about a 25% reduction in the case of 4.5V biasing.

The cross-section views in <figref idref="DRAWINGS">FIGS. 2A-2K</figref> are merely illustrative and are not intended to limit the layout or other structural aspects of the cell array. Furthermore, these figures may not accurately reflect the actual shape of all the various regions as they would appear in an actual device. <figref idref="DRAWINGS">FIG. 5</figref> is an exemplary cross-section view corresponding to that in <figref idref="DRAWINGS">FIG. 2K</figref>, and is provided to show a more accurate representation of the contours of the trenches in accordance with one embodiment of the invention. Because of the small dimensions of some of the regions and the effects of such processing steps as temperature cycles, a rounding of many of the corners occurs during processing. As a result, the trenches appear Y-shaped as shown in <figref idref="DRAWINGS">FIG. 5</figref> rather than T-shaped as shown in <figref idref="DRAWINGS">FIG. 2K</figref>. However, it is to be understood that the invention is not limited to a particular shape of the trenches.

While the above is a complete description of the embodiments of the present invention, it is possible to use various alternatives, modifications and equivalents. For example, the process steps depicted in <figref idref="DRAWINGS">FIGS. 2A-2K</figref> are for manufacturing an N-channel MOSFET. Modifying these process steps to obtain an equivalent P-channel MOSFET would be obvious to one skilled in the art in light of the above teachings. Similarly, modifying the process steps to obtain other types of semiconductor devices such as insulated gate bipolar transistor (IGBT) would be obvious to one skilled in the art in light of the above teachings.

Also, body region 214 (<figref idref="DRAWINGS">FIG. 2F</figref>) may be formed earlier in the processing sequence. For example, in <figref idref="DRAWINGS">FIG. 2A</figref>, prior to forming regions 206, P-type impurities may be implanted into epitaxial layer 204 or a P-type epitaxial layer may be grown over epitaxial layer 204. Similarly, N-type regions 216 (<figref idref="DRAWINGS">FIG. 2F</figref>) may be formed earlier in the processing sequence. For example, a blanket implant of N-type impurities may be carried out to form a highly-doped N-type region in the body region before forming the trenches. The highly-doped N-type region however needs to extend deeper into the body region than that depicted in <figref idref="DRAWINGS">FIG. 2F</figref> so that after the trenches are formed, at least a portion of the N-type region extends below the outer sections of the trenches. Also, a deeper silicon etch would be required in <figref idref="DRAWINGS">FIG. 2J</figref> in order to reach a surface of the body region.

In a further variation, epitaxial layer 204 may have a graded doping concentration rather than a fixed doping concentration, or may be made of a number of epitaxial layers each having a different doping concentration, or may be eliminated all together depending on the design goals. Moreover, the trenches may extend clear through epitaxial layer 204 and terminate within substrate 202.

Therefore, the scope of the present invention should be determined not with reference to the above description but should, instead, be determined with reference to the appended claim, along with their full scope of equivalents.

Contents5

Every citation, both waysCites: the store holds 289 of 290

Citations
Document	Relation	Office	Cited during
US8878286B2	Cited by	United States of America	Applicant
US2010140696A1	Cited by	United States of America	Pre-grant
US9324837B2	Cited by	United States of America	Applicant
US8710582B2	Cited by	United States of America	Search report
US12302602B2	Cited by	United States of America	Applicant
US9842925B2	Cited by	United States of America	Applicant
US9401436B2	Cited by	United States of America	Applicant
US8859365B2	Cited by	United States of America	Search report
US9184261B2	Cited by	United States of America	Applicant
US8658491B2	Cited by	United States of America	Applicant
US8669623B2	Cited by	United States of America	Applicant
US10868113B2	Cited by	United States of America	Applicant
US2013069146A1	Cited by	United States of America	Pre-grant
US2009315083A1	Cited by	United States of America	Pre-grant
US9748329B2	Cited by	United States of America	Applicant
US8466513B2	Cited by	United States of America	Applicant
US2010207205A1	Cited by	United States of America	Pre-grant
US9450091B2	Cited by	United States of America	Applicant
US9853126B2	Cited by	United States of America	Applicant
US2012168819A1	Cited by	United States of America	Pre-grant
US7807576B2	Cited by	United States of America	Search report
US9142667B2	Cited by	United States of America	Applicant
US2010140695A1	Cited by	United States of America	Pre-grant
US9530883B2	Cited by	United States of America	Applicant
US2011014762A1	Cited by	United States of America	Pre-grant
US2011003449A1	Cited by	United States of America	Pre-grant
US2010200910A1	Cited by	United States of America	Pre-grant
US7825464B2	Cited by	United States of America	Search report
US9818845B2	Cited by	United States of America	Applicant
US2010140689A1	Cited by	United States of America	Pre-grant
US2010314707A1	Cited by	United States of America	Pre-grant
US8778764B2	Cited by	United States of America	Applicant
US2010320534A1	Cited by	United States of America	Pre-grant
US2010015769A1	Cited by	United States of America	Pre-grant
US2014179075A1	Cited by	United States of America	Pre-grant
US9269779B2	Cited by	United States of America	Applicant
US2010140697A1	Cited by	United States of America	Pre-grant
US2009159988A1	Cited by	United States of America	Pre-grant
US9553185B2	Cited by	United States of America	Applicant
US8907394B2	Cited by	United States of America	Applicant
US2003107080A1	Cites	United States of America	Search report
US3404295A	Cites	United States of America	Applicant
US3412297A	Cites	United States of America	Applicant
US3497777A	Cites	United States of America	Applicant
US3564356A	Cites	United States of America	Applicant
US4003072A	Cites	United States of America	Applicant
US4300150A	Cites	United States of America	Applicant
US4326332A	Cites	United States of America	Applicant
US4337474A	Cites	United States of America	Applicant
US4579621A	Cites	United States of America	Applicant
US4636281A	Cites	United States of America	Applicant
US4638344A	Cites	United States of America	Applicant
US4639761A	Cites	United States of America	Applicant
US4698653A	Cites	United States of America	Applicant
US4716126A	Cites	United States of America	Applicant
US4746630A	Cites	United States of America	Applicant
US4754310A	Cites	United States of America	Applicant
US4774556A	Cites	United States of America	Applicant
US4801986A	Cites	United States of America	Applicant
US4821095A	Cites	United States of America	Applicant
US4823176A	Cites	United States of America	Applicant
US4853345A	Cites	United States of America	Applicant
US4868624A	Cites	United States of America	Applicant
US4893160A	Cites	United States of America	Applicant
US4914058A	Cites	United States of America	Applicant
US4941026A	Cites	United States of America	Applicant
US4967245A	Cites	United States of America	Applicant
US4974059A	Cites	United States of America	Applicant
US4990463A	Cites	United States of America	Applicant
US4992390A	Cites	United States of America	Applicant
US5027180A	Cites	United States of America	Applicant
US5071782A	Cites	United States of America	Applicant
US5072266A	Cites	United States of America	Applicant
US5079608A	Cites	United States of America	Applicant
US5105243A	Cites	United States of America	Applicant
US5142640A	Cites	United States of America	Applicant
US5164325A	Cites	United States of America	Applicant
US5164802A	Cites	United States of America	Applicant
US5216275A	Cites	United States of America	Applicant
US5219777A	Cites	United States of America	Applicant
US5219793A	Cites	United States of America	Applicant
US5233215A	Cites	United States of America	Applicant
US5262336A	Cites	United States of America	Applicant
US5268311A	Cites	United States of America	Applicant
US5275965A	Cites	United States of America	Applicant
US5283201A	Cites	United States of America	Applicant
US5294824A	Cites	United States of America	Applicant
US5298781A	Cites	United States of America	Applicant
US5300447A	Cites	United States of America	Applicant
US5326711A	Cites	United States of America	Applicant
US5350937A	Cites	United States of America	Applicant
US5365102A	Cites	United States of America	Applicant
US5366914A	Cites	United States of America	Applicant
US5389815A	Cites	United States of America	Applicant
US5405794A	Cites	United States of America	Applicant
US5418376A	Cites	United States of America	Applicant
US5424231A	Cites	United States of America	Applicant
US5429977A	Cites	United States of America	Applicant
US5430311A	Cites	United States of America	Applicant
US5430324A	Cites	United States of America	Applicant

Showing 100 of 383

264 members in 12 offices

This recordMember, by publication datePriority claim2 more offices are in the list below

Priority claims6

Priority claims
Document	Office	Kind	Date
44267003	United States of America	A	2003-05-20
44267003	United States of America	A	2003-05-20
11130505	United States of America	A	2005-04-20
10442670	–	–	–
US20030442670	–	–	–
US20050111305	–	–	–

Members264

Family members, oldest first
Document	Office	Kind
EP0923137A2	European Patent Office (EPO)	A2	1999-06-16
KR19990045294A	Republic of Korea	A	1999-06-25
CN1227418A	China	A	1999-09-01
JPH11243196A	Japan	A	1999-09-07
EP0923137A3	European Patent Office (EPO)	A3	2000-02-02
DE10062542A1	Germany	A1	2001-06-21
JP2001203310A	Japan	A	2001-07-27
SG83108A1	Singapore	A1	2001-09-18
US2001023104A1	United States of America	A1	2001-09-20
TW465047B	Taiwan Province of China	B	2001-11-21
TW473966B	Taiwan Province of China	B	2002-01-21
US2002100933A1	United States of America	A1	2002-08-01
US2002100962A1	United States of America	A1	2002-08-01
US6429481B1	United States of America	B1	2002-08-06
WO02061832A1	World Intellectual Property Organization (WIPO)	A1	2002-08-08
US2002140027A1	United States of America	A1	2002-10-03
US6469384B2	United States of America	B2	2002-10-22
US2003011005A1	United States of America	A1	2003-01-16
US6521497B2	United States of America	B2	2003-02-18
US2003038615A1	United States of America	A1	2003-02-27
WO03019761A1	World Intellectual Property Organization (WIPO)	A1	2003-03-06
US2003071320A1	United States of America	A1	2003-04-17
US2003073287A1	United States of America	A1	2003-04-17
WO03034470A2	World Intellectual Property Organization (WIPO)	A2	2003-04-24
AU2002335103A1	Australia	A1	2003-04-28
TW535243B	Taiwan Province of China	B	2003-06-01
US2003127688A1	United States of America	A1	2003-07-10
US2003141522A1	United States of America	A1	2003-07-31
WO03034470A3	World Intellectual Property Organization (WIPO)	A3	2003-09-12
US6677641B2	United States of America	B2	2004-01-13
US2004014451A1	United States of America	A1	2004-01-22
US2004021173A1	United States of America	A1	2004-02-05
WO2004019380A2	World Intellectual Property Organization (WIPO)	A2	2004-03-04
AU2003262748A1	Australia	A1	2004-03-11
AU2003262748A8	Australia	A8	2004-03-11
US6710403B2	United States of America	B2	2004-03-23
US6710406B2	United States of America	B2	2004-03-23
US2004056364A1	United States of America	A1	2004-03-25
US6713813B2	United States of America	B2	2004-03-30
US2004063269A1	United States of America	A1	2004-04-01
US6717230B2	United States of America	B2	2004-04-06
US6720642B1	United States of America	B1	2004-04-13
CN1489788A	China	A	2004-04-14
DE10295972T5	Germany	T5	2004-04-15
US2004084721A1	United States of America	A1	2004-05-06
TW587328B	Taiwan Province of China	B	2004-05-11
US6740541B2	United States of America	B2	2004-05-25
TW200409458A	Taiwan Province of China	A	2004-06-01
US2004113202A1	United States of America	A1	2004-06-17
KR20040062570A	Republic of Korea	A	2004-07-07
US2004132252A1	United States of America	A1	2004-07-08
JP2004521493A	Japan	A	2004-07-15
US2004135201A1	United States of America	A1	2004-07-15
US2004145015A1	United States of America	A1	2004-07-29
US2004164386A1	United States of America	A1	2004-08-26
DE10297140T5	Germany	T5	2004-09-02
US6803626B2	United States of America	B2	2004-10-12
US6818513B2	United States of America	B2	2004-11-16
US2004232481A1	United States of America	A1	2004-11-25
WO2004105090A2	World Intellectual Property Organization (WIPO)	A2	2004-12-02
US6828195B2	United States of America	B2	2004-12-07
TW200428523A	Taiwan Province of China	A	2004-12-16
WO2004109789A1	World Intellectual Property Organization (WIPO)	A1	2004-12-16
US2004256690A1	United States of America	A1	2004-12-23
JP2005501497A	Japan	A	2005-01-13
CN1568568A	China	A	2005-01-19
DE10297349T5	Germany	T5	2005-01-27
US2005023607A1	United States of America	A1	2005-02-03
US2005029618A1	United States of America	A1	2005-02-10
JP2005507160A	Japan	A	2005-03-10
US6870217B2	United States of America	B2	2005-03-22
US6870220B2	United States of America	B2	2005-03-22
CN1605119A	China	A	2005-04-06
US2005079676A1	United States of America	A1	2005-04-14
KR20050038025A	Republic of Korea	A	2005-04-25
US6906362B2	United States of America	B2	2005-06-14
US2005145934A1	United States of America	A1	2005-07-07
US2005146372A1	United States of America	A1	2005-07-07
US6916745B2	United States of America	B2	2005-07-12
WO2005065385A2	World Intellectual Property Organization (WIPO)	A2	2005-07-21
DE10393138T5	Germany	T5	2005-07-28
US2005167742A1	United States of America	A1	2005-08-04
US2005167848A1	United States of America	A1	2005-08-04
TW200527701A	Taiwan Province of China	A	2005-08-16
US6930473B2	United States of America	B2	2005-08-16
US2005191794A1	United States of America	A1	2005-09-01
US6949410B2	United States of America	B2	2005-09-27
US6953998B2	United States of America	B2	2005-10-11
WO2004105090A3	World Intellectual Property Organization (WIPO)	A3	2005-11-17
US2005272209A1	United States of America	A1	2005-12-08
US2005280126A1	United States of America	A1	2005-12-22
US2005280161A1	United States of America	A1	2005-12-22
WO2004019380A3	World Intellectual Property Organization (WIPO)	A3	2005-12-22
US2006011962A1	United States of America	A1	2006-01-19
US6991977B2	United States of America	B2	2006-01-31
US7005353B2	United States of America	B2	2006-02-28
JP2006511932A	Japan	A	2006-04-06
WO2005065385A3	World Intellectual Property Organization (WIPO)	A3	2006-04-06
KR20060036385A	Republic of Korea	A	2006-04-28
KR100551190B1	Republic of Korea	B1	2006-05-25

Showing 100 of 264

34 transactions on the USPTO file

Allowed after 1 non-final rejection.

Non-final rejections: 1
Final rejections: 0
RCEs: 0
Appeals: 0

Over time

Point at a mark for the transaction

Transactions

Prosecution transactions, newest first
	Event	Code
2019-08-21	Payment of Maintenance Fee, 12th Year, Large EntityM1553	M1553
2008-03-18	Recordation of Patent Grant MailedPGM/	PGM/
2008-03-18	Patent Issue Date Used in PTA CalculationAllowedPTAC	PTAC
2008-02-27	Issue Notification MailedAllowedWPIR	WPIR
2008-02-11	Dispatch to FDCD1935	D1935
2008-02-11	Application Is Considered Ready for IssuePILS	PILS
2008-01-22	Issue Fee Payment VerifiedN084	N084
2008-01-22	Issue Fee Payment ReceivedIFEE	IFEE
2007-10-18	Mail Notice of AllowanceAllowedMN/=.	MN/=.
2007-10-16	Notice of Allowance Data Verification CompletedAllowedN/=.	N/=.
2007-10-16	Case Docketed to Examiner in GAUDOCK	DOCK
2007-08-02	Date Forwarded to ExaminerFWDX	FWDX
2007-07-31	Information Disclosure Statement consideredIDSC	IDSC
2007-07-31	Information Disclosure Statement consideredIDSC	IDSC
2007-07-31	Information Disclosure Statement (IDS) FiledWIDS	WIDS
2007-07-31	Information Disclosure Statement (IDS) FiledM844	M844
2007-07-31	Response after Non-Final ActionA...	A...
2007-07-31	Information Disclosure Statement (IDS) FiledWIDS	WIDS
2007-05-31	Mail Non-Final RejectionNon-final rejectionMCTNF	MCTNF
2007-05-29	Non-Final RejectionNon-final rejectionCTNF	CTNF
2007-04-17	Case Docketed to Examiner in GAUDOCK	DOCK
2007-04-17	Transfer Inquiry to GAUTI1050	TI1050
2007-03-14	Case Docketed to Examiner in GAUDOCK	DOCK
2005-06-07	IFW TSS Processing by Tech Center CompleteTSSCOMP	TSSCOMP
2005-06-07	Case Docketed to Examiner in GAUDOCK	DOCK
2005-05-24	Application Is Now CompleteCOMP	COMP
2005-05-23	Application Return from OIPEWROIPE	WROIPE
2005-05-23	Application Return TO OIPEROIPE	ROIPE
2005-05-23	Application Dispatched from OIPEOIPE	OIPE
2005-05-23	Application Is Now CompleteCOMP	COMP
2005-05-11	Cleared by L&R (LARS)L128	L128
2005-05-09	Referred to Level 2 (LARS) by OIPE CSRL198	L198
2005-05-04	IFW Scan & PACR Auto Security ReviewSCAN	SCAN
2005-04-20	Initial Exam Team nnIEXX	IEXX

15 legal events, as the office reported them to INPADOC

Over the term

Point at a mark for the event

Events

Legal events, newest first
	Event	Code
2023-06-23	AssignmentAS	AS
2023-06-23	AssignmentAS	AS
2023-06-22	AssignmentAS	AS
2023-06-22	AssignmentAS	AS
2021-11-12	AssignmentAS	AS
2021-10-28	AssignmentAS	AS
2021-10-28	AssignmentAS	AS
2021-08-03	AssignmentAS	AS
2021-08-03	AssignmentAS	AS
2019-08-21	Maintenance fee paymentMAFP	MAFP
2016-09-19	AssignmentAS	AS
2016-09-19	AssignmentAS	AS
2015-08-27	Fee paymentFPAY	FPAY
2011-09-19	Fee paymentFPAY	FPAY
2008-02-27	Information on status: patent grantGrantedPATENTED CASESTCF	STCF

Method for forming a trench MOSFET having self-aligned features

Summary by NHIP

Claim Score by NHIP

Abstract